I guess nothing can happen except if he will be converting his holding to cash in the many exchanges that we have right now. Now, having said that, I think a big news like this can even be helping Bitcoin as people will now see the man behind the Bitcoin and maybe can also provide the leadership and guidance sorely needed. Of course, this is just my personal opinion and I could not predict the future in any way. However, this can be just a wishful thinking as nobody can be sure if Satoshi Nakamoto is still alive and if he was a real person in the first place.